Ancient Great Power Conflict: A Roman Counterpoint to Thucydides
The change in Presidential administrations will likely include an update to U.S. policies concerning China. There will likely be a renewed interest in Graham Allison’s “Thucydides Trap,” which claims that the ancient historian’s explanation of the Peloponnesian War uncovered a permanent feature of great power rivalry: the likelihood that leading powers and rising challengers will go to war. Many scholars and policymakers share that fear, joining Allison in worrying that war between the U.S. and China may be inevitable in the near future. However, aspects of another ancient rivalry question that pessimism. The 2nd century rivalry between Rome and Parthia shows that war between great powers is often a choice, and that modern leaders can and should consider the impact of their decisions before choosing conflict. It would be wise for President Trump’s security team to explore more than just Athens and Sparta when they look to the past for possible solutions to modern problems.
Rome’s Rival
Rome and Parthia challenged each other for centuries. On the surface, their rivalry appears to be a poor case for refuting the Thucydides Trap, since open warfare between the two empires happened more than once. However, the fact that the two empires existed for hundreds of years while sharing a border, and that there were significant periods of time where the two were not at war, demonstrates that many factors shape the prospects for war between major powers.
A key period of peace between the two states existed during the rule of Emperor Hadrian. He had an accomplished military record before rising to power, and was not unwilling to commit Roman troops to combat. However, the man that classic British historian Edward Gibbon described as prudent and moderate in his governance was more interested in consolidating his Empire than expanding it. This was a departure from many of his predecessors, and was generally welcomed by the Roman public.
Hadrian’s predecessor Trajan fought a major war from AD 114-117 that succeeded in wrestling significant new territory away from their eastern neighbor the Parthian Empire. The result of his conquest was the addition of three new provinces, east of the Euphrates River, to the Roman Empire. However, rebellions at home and the significant need for garrison troops in the new territory had stretched the vaunted Roman military thin. One of Hadrian’s first acts upon Trajan’s death was to relinquish control of the new territories, and re-establish the former boundary on the Euphrates. He also arranged for a now-dispossessed client king to receive control over different lands. These were the acts of a leader preferring stability over conflict.
Throughout his reign Hadrian traveled the Empire, and along the way, oversaw or commissioned the development of physical barriers along borders. Wooden forts with palisades, ditches, and walls were all constructed under his orders to delineate Roman territory and support his consolidation efforts. His best-known project was the wall across modern England that still bears his name. In AD 124 he traveled to the Roman-Parthian border and personally met with his Parthian counterpart King Chosroes. Although the specific details are lost, historical events show they negotiated a continued peace between the Empires. He returned to the Eastern Roman provinces in AD 129 and may have had a repeat summit with Parthian Leaders. The goal was again to sustain a lasting peace. Towards that end, Hadrian even authorized the release of Chosroes’s daughter from her capture and imprisonment by Trajan.
Trump and Xi both have choices, just as Hadrian and Chosroes did. Neither may choose to step back from potential conflict, particularly from their positions on Taiwan, but the choice to do so exists.
After Hadrian’s death in AD 138, his successor Antoninus Pius continued to choose diplomacy over war with Parthia, keeping Hadrian’s agreements in place. Even as the two great powers eyed each other warily and jostled for military advantage, rulers on both sides chose years of negotiations over war. The peace held until AD 163, when Pius’ successor, Marcus Aurelius, invaded over a disagreement over the disposition of Armenia. Yet Hadrian’s choices had resulted in 46 years of peace between the two powers, despite the relative “rise” of Parthia after Trajan’s retreat. The two states avoided the “Thucydides Trap” through negotiation and deliberate choices to avoid conflict.
Avoiding Thucydides’ Trap
If one believes that great powers are motivated to fight, then the reign of Hadrian should have continued the conflicts of Trajan. Yet, Hadrian made difficult choices that avoided war with Parthia for an entire generation; forty-six years is a considerable period for stable international relations of any era. Leaders are replaced and new issues arise, as inevitable shifts in relative power reshape assessments of dangers and opportunities. Even an autocrat will have to adapt to a changing world over that stretch of time, and continuously make decisions to continue or alter the state’s international relations. Hadrian chose repeatedly to secure the Roman Empire by taking steps to avoid war with his greatest rival.
War occurred between the two empires again in AD 163, suggesting again that this is a less than perfect analogy for the U.S. and China. One could also arguably set aside the Rome and Parthia example because the two also did not face such modern issues as the instantaneous gathering and analysis of information, or the speed and reach of air and space-based assets. Nor did those ancient rivals have to deal with the quandaries attending to the dangers posed by nuclear weapons. However, one could play “what if” with any ancient analogy, at the cost of failing to draw valuable lessons from the past.
There are important similarities between the choices faced by ancient and modern leaders. Trump and Xi both have choices, just as Hadrian and Chosroes did. Neither may choose to step back from potential conflict, particularly from their positions on Taiwan, but the choice to do so exists. It would be helpful if the policy community could move past preoccupation with the “Thucydides Trap” and realize that a range of options exists for peaceful coexistence between the U.S. and China. Hadrian had a vast array of competing interests as Trump and Xi will. He chose the peace and stability of the Roman Empire over the previous path of conquest and expansion. He faced pushback, particularly from the Roman elites, yet held to the course that avoided war. His descendants eventually chose otherwise, reflecting the inevitability of change in international arrangements. Yet this does not change he chose not to act based on the supposition that shifts in the balance of power made another Parthian war inevitable. He had choices, and chose peace. U.S. and Chinese leadership can and hopefully will choose to do the same.
Disclaimer: The views expressed in this article are those of the author and do not necessarily reflect the official policy or position of the United States Air Force Academy, the Air Force, the Department of Defense, or the U.S. Government.
